On Mon, May 06, 2013 at 11:16:40PM -0400, Olivier Langlois wrote: > On Tue, 2013-05-07 at 01:47 +0200, Frederic Weisbecker wrote: > > On Fri, May 03, 2013 at 12:47:42AM -0400, kosaki.motoh...@gmail.com wrote: > > > From: KOSAKI Motohiro <kosaki.motoh...@jp.fujitsu.com> > > > > > > When tsk->signal->cputimer->running is 1, signal->cputimer and > > > tsk->sum_sched_runtime increase at the same pace because update_curr() > > > increases both accounting. > > > > > > However, there is one exception. When thread exiting, __exit_signal() > > > turns > > > over task's sum_shced_runtime to sig->sum_sched_runtime, but it doesn't > > > stop > > > signal->cputimer accounting. > > > > > > This inconsistency makes POSIX timer wake up too early. This patch fixes > > > it. > > > > > > Cc: Thomas Gleixner <t...@linutronix.de> > > > Cc: Frederic Weisbecker <fweis...@gmail.com> > > > Cc: Ingo Molnar <mi...@kernel.org> > > > Acked-by: Peter Zijlstra <pet...@infradead.org> > > > Signed-off-by: Olivier Langlois <oliv...@trillion01.com> > > > Signed-off-by: KOSAKI Motohiro <kosaki.motoh...@jp.fujitsu.com> > > > --- > > > kernel/sched/stats.h | 7 +++++++ > > > 1 files changed, 7 insertions(+), 0 deletions(-) > > > > > > diff --git a/kernel/sched/stats.h b/kernel/sched/stats.h > > > index 2ef90a5..5a0cfc4 100644 > > > --- a/kernel/sched/stats.h > > > +++ b/kernel/sched/stats.h > > > @@ -225,6 +225,13 @@ static inline void account_group_exec_runtime(struct > > > task_struct *tsk, > > > if (!cputimer->running) > > > return; > > > > > > + /* > > > + * After turning over se.sum_exec_runtime to sig->sum_sched_runtime > > > + * in __exit_signal(), we must not account exec_runtime for > > > consistency. > > > + */
Please just precise the nature of that consistency: the fact we want CLOCK_PROCESS_CPUTIME_ID clock and timer to be consistent. > > > + if (unlikely(!tsk->sighand)) > > > + return; > > > > Ok, if we want the clock and timer to be consistent, do we also want the > > same check in > > account_group_user_time() and account_group_system_time()? The task can > > still account > > a tick after autoreaping itself between release_task() and the final > > schedule(). > > > If I can reply, I believe that Kosaki refactoring is superior to my > initial proposal because: > > 1. Condition will only be evaluated when cputimer is on (and not slow > down scheduler when it is off) > 2. It handles all the cases when this function is called. There are few > other places outside update_curr() that this function is called. Agreed. Thanks! Acked-by: Frederic Weisbecker <fweis...@gmail.com> -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
